An SPVC connection between two endpoints consists of a user configured Permanent Virtual Circuit (PVC) portion and a dynamically established Switched Virtual Circuit (SVC) portion. The path through the network for the SVC portion of the call can be automatically computed using PNNI routing or can be configured a priori by the network administrator. This path, which is referred to as a DTL, comprises the complete list of logical nodes (and possibly logical links) that the connection is to traverse across the network. In a hierarchical PNNI network, a DTL will consist of logical nodes and links at all levels of the hierarchy between the originating and terminating nodes.
A remote transit peer groups in a hierarchically complete DTL is represented by the complete node ID of the Logical Group Node (LGN) representing the peer group in the hierarchy. If the switching system functioning as the Peer Group Leader (PGL) of a remote peer group fails, the node ID of the LGN representing that peer group will change. This will in effect invalidate all DTLs transiting this peer group that were configured by the operator prior to the failure. Any new SPVCs setup using these DTLs will fail possibly resulting in a service impacting outage. Currently, the only way to recover from this situation is for the network administrator to reconfigure all these DTLs to use the node ID of the new LGN representing the peer group in question.
The invention described herein prevents such failures from occurring by changing the way hops are represented in a hierarchical DTL.